6x6

schröder staircase: prize-winning optical illusions 

well, the spam, eggs, sausage and spam—that’s not got much spam in it: McDonald’s in China releases a special, limited edition burger  

every day, the same, again: miscellany from the New Shelton wet/dry 

black mirror: a Claude glass was a handheld Instagram filter of artists and sightseers in the late 1700s

back contamination: NASA’s efforts to contain a lunar pandemic (see previously) that never came to pass and what lessons it can teach us in this current situation

frame-included position shift: another impressive optical illusion